1. Technical Field
The present invention relates to a method for checking the operation of anti-skid system incorporated in motor vehicles.
2. Prior Art
It is known that the anti-skid brake system of motor vehicles operates in response to the lowest wheel peripheral speed among a plurality of wheels for controlling the brake force so as to prevent skid against the road surface.
Japanese Laid-Open Patent Application (Kokai) No. 59-184052, published Oct. 19, 1984, discloses a method for checking the anti-skid brake system comprising the steps of electing one pseudo wheel-speed signal among pseudo wheel-signals in accordance with each operating condition produced in a pseudo signal generator while the vehicle is stopped, inputting the pseudo wheel-speed signal to the anti-skid brake system, and confirming the oscillation of the hydraulic pressure in the anti-skid brake system responsive to the pseudo wheel-speed signal, that is interrupting anti-skid control during the normal decelerating condition or always in response to the lowest wheel peripheral speed among a plurality of wheels.
Furthermore, there has been also devised and disclosed in Japanese Laid-Open Patent Application (Kokai) No. 61-36008 published Feb. 20, 1986 a method for a self-diagnosing system of electronic devices mounted on motor vehicles, comprising the steps of providing a self-diagnosis start switching means at a position at which the driver can operate it and further providing self-diagnosis-start control means for starting the self-diagnosis when the switching signals are delivered from the self-diagnosis start switching means in excess of a predetermined number within a predetermined time period, whereby the starting of the self-diagnosis can be commanded directly from the driver's seat and an erroneous operation can be prevented when a vehicle is in the normal running mode.
In the method for detecting the oscillation of the hydraulic pressure produced in a wheel cylinder in the case of the inspection of the anti-skid brake action as is disclosed in the first-mentioned application (Japanese Laid-Open Patent Application No. 59-184052), it is of course needed to additionally provide a sensor for detecting the oscillation of the hydraulic pressure in each wheel cylinder. In addition, in the case where an anti-skid brake-action sensing device is fabricated as a unitary construction so that it can be detached from the vehicle body to be carried freely, a confirmation lamp included in the anti-skid brake-action diagnosis device must be connected through connecting terminals to the hydraulic-pressure-oscillation sensor incorporated in the wheel cylinder.
In the case of the second mentioned prior art method (Japanese Laid-Open Patent Application No. 61-36008), only the self-diagnosis for detecting whether or not the correct arithmetic operations are executed by an electronic control device is effected, and it is impossible to detect whether or not the actual operation of a mechanism activated in response to the results of the arithmetic operations executed by the electronic control device is correct.